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Firefighting Precautions at Facilities with Combustible Dust

Firefighting Precautions at Facilities with Combustible DustOSHA 3644-04 2013 Occupational Safety and Health Act of 1970 To assure safe and healthful working conditions for working men and women; by authorizing enforcement of the standards developed under the Act; by assisting and encouraging the States in their efforts to assure safe and healthful working conditions; by providing for research, information, education, and training in the field of occupational safety and health. Cover photo: Todd Dudek, Gannett Newspapers. This image is for informational purposes only and does not represent an official OSHA endorsement of the products shown or their contained in this publication is in the public domain and may be reproduced, fully or partially, without permission.

Unknown location, 2004: two firefighters injured. A National Fire Protection Association (NFPA) report on firefighter injuries described a smoldering fire in ductwork at a furniture manufacturing company. Plant personnel told the fire department that the associated dust collector had been shut down, but it had not.

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Transcription of Firefighting Precautions at Facilities with Combustible Dust

1 Firefighting Precautions at Facilities with Combustible DustOSHA 3644-04 2013 Occupational Safety and Health Act of 1970 To assure safe and healthful working conditions for working men and women; by authorizing enforcement of the standards developed under the Act; by assisting and encouraging the States in their efforts to assure safe and healthful working conditions; by providing for research, information, education, and training in the field of occupational safety and health. Cover photo: Todd Dudek, Gannett Newspapers. This image is for informational purposes only and does not represent an official OSHA endorsement of the products shown or their contained in this publication is in the public domain and may be reproduced, fully or partially, without permission.

2 Source credit is requested but not information will be made available to sensory- impaired individuals upon request. Voice phone: (202) 693-1999; teletypewriter (TTY) number: 1-877-889-5627. This publication provides a general overview of a particular standards-related topic. This publication does not alter or determine compliance responsibilities which are set forth in OSHA standards, and the Occupational Safety and Health Act. Moreover, because interpretations and enforcement policy may change over time, for additional guidance on OSHA compliance requirements, the reader should consult current administrative interpretations and decisions by the Occupational Safety and Health Review Commission and the Precautions at Facilities with Combustible DustOccupational Safety and Health Department of LaborOSHA 3644-04 2013 TABLE OF CONTENTSI ntroduction.

3 1 How does a Combustible dust explosion occur? ..1 What do previous incidents illustrate? ..2 What preparations can be made prior to a response? ..4 Pre-incident survey ..4 Trade secrets ..5 Safety Data Sheets ..5 Hybrid mixtures ..5 protection systems ..5 Facility liaison ..6 Equipment compatibility ..6 How should this preparation affect the operational plan? ..6 What Precautions can be taken during a response? ..7 fire Attack Mode ..7 Extinguishing Agent Selection ..8 fire Extinguisher Use ..9 Hose Stream Use ..9 fire Safety Systems ..10 Access ..10 Ventilation ..11 Power Shutdown ..11 Tool and Equipment Use ..12 Where can I find additional information? ..13 Appendix A Dust Collection Equipment ..14 Appendix B Storage Methods ..17 Appendix C Process Equipment.

4 20 Appendix D Pneumatic Conveying Equipment ..22 OSHA Regional Offices ..24 How to Contact OSHA ..25 Firefighting Precautions AT Facilities with Combustible DUST1 IntroductionEvery year, a number of emergency responders are injured, and sometimes killed, during emergency operations in Facilities where Combustible dusts exist. In some cases, responders have inadequate information or training on the explosible1 characteristics of Combustible dust and/or the conditions present in the facility, which has increased the challenge of handling incidents safely and there is a delay or setback during an incident, the risk of injury rises for facility workers as well as for emergency responders. Everyone is safer when facility and emergency personnel share information and develop safe procedures to handle incidents involving Combustible dusts.

5 Owners, operators, and the community also benefit from reduced property damage when incidents are handled quickly and primary purpose of this document is to protect emergency responders from harm by giving them a framework for gathering the necessary information prior to an emergency and converting it into safe operating procedures. In this document, emergency responders include firefighters, fire brigade members, hazardous materials teams, and others who might be called upon to respond when a fire or explosion document is not intended to provide specific strategies or tactics to be used during emergency responses. It does, however, discuss some tactics that should be considered. The information presented here and collected during pre-incident surveys should be used to train all emergency responders on how to properly handle incidents at Facilities with Combustible dusts.

6 The information presented in this publication is limited to the fire and explosion hazards of Combustible dust. Facilities with Combustible dust may have other hazards for emergency responders to consider, such as engulfment, electric shock, unguarded machinery and chemical Explosible materials are capable of exploding; Combustible dusts become capable of exploding when finely divided and dispersed as described in the next section. Explosive materials can explode as is; their main purpose is to function by does a Combustible dust explosion occur?Firefighters are well aware of the elements of the fire triangle : fuel, heat, and oxygen (see figure 1). In this case, Combustible dust is the fuel. Oxygen is usually available in the ambient air. In addition to, or in place of the oxygen, another chemical oxidizer may simulate oxygen in the combustion reaction.

7 The following information discusses the additional elements needed for a flash fire or explosion to 1. fire TriangleJust about any solid material that burns can be explosible when finely divided into a dust. For example, a piece of wood can become explosible when reduced to sawdust. Even materials that do not burn in larger pieces (such as aluminum or iron) can be explosible in dust form. In school or training, you may have seen a demonstration involving a small container with flour or a similar material that was ignited, created a small fireball, and forced the lid of the container to lift. This can occur on a much larger scale in a building or confined Combustible dust in the proper concentration is dispersed in a cloud, and then ignited, a flash fire occurs (see figure 2).

8 This flash fire is like a larger version of the fireball in the classroom demonstration. It is much more dangerous to humans than an ordinary fire because it spreads too quickly to outrun. You may hear the term deflagration ; this is a type of flash fire that is strong enough to cause damage to equipment or SAFETY AND HEALTH ADMINISTRATION2 FUELHEATDISPERSIONDUSTCLOUDOXYGENF igure 2. Elements of a Flash Fire2 When a flash fire is confined, the pressure that develops can cause an explosion, damaging or destroying the confining enclosure (see figure 3). This explosion is a larger version of the lifting lid in the classroom demonstration above. The confining enclosure could be processing equipment, a conveyor, a dust collector, a room, or an entire building.

9 The flying shrapnel, blast wave and collapsing structural members resulting from the explosion can injure or kill individuals over a large area. FUELOXYGENDISPERSIONHEATCONFINEMENTF igure 3. Explosion PentagonThe blast wave can also disperse accumulated Combustible dust in work or storage areas, fueling one or more subsequent explosions. These secondary explosions are often more destructive than the initial incident due to the large quantities of dust dispersed. Secondary explosions can continue to ignite in sequence, cascading throughout a This four-sided representation of flash fire elements should not be confused with a fire tetrahedron, which adds an element (chemical chain reaction) to the fire triangle to explain how certain agents extinguish a do previous incidents illustrate?

10 Firefighting operations can inadvertently increase the chance of a Combustible dust explosion if they: Use tactics that cause dust clouds to form or reach the explosible range. Use tactics that introduce air, creating an explosible atmosphere. Apply incorrect or incompatible extinguishing agents. Use equipment or tools that can become an ignition examples below illustrate these general principles in specific incidents. In some examples, Combustible dust fueled the entire event; in others, Combustible dust may have contributed to it. In most cases, the initial ignition sequence is unknown or unreported. South Dakota, 2011: two firefighters killed. According to a national Institute for Occupational Safety and Health (NIOSH) report, a fire occurred in a coal bin that fed a boiler.


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